1) Field of the Invention
The invention relates to a device for projecting an image on a surface, comprising:                a light source generating a light beam;        a mask arranged in the path of the light beam;        a lens arranged behind the mask to focus the image of the mask on a surface, wherein the surface is not parallel to the lens.        
2) Description of the Prior Art
In particular in the field of pulsed laser deposition (PLD) it is important to control the projection of an image on a surface. With PLD a laser light beam is projected under an angle onto a surface of an ablatable material. The projected image is a spot in which the energy of the laser light beam is concentrated. This energy causes the material of the surface to evaporate into a plasma plume, which plume can be used to coat the surface of a substrate.
With PLD it is important that the spot, which is the image of the mask, is homogeneous, such that the laser energy is distributed evenly. This is necessary to have a plasma plume which corresponds in composition to the solid material of the surface on which the spot is projected. If the spot is not homogeneous it is possible that some components of the material of the surface go into the plasma phase, some components only melt and form drops and some components stay solid.
As with PLD the light beam is generally projected under an angle onto the surface, the spot will always be somewhat inhomogeneous. This inhomogeneity will be more prominent as the angle between the light beam and the surface decreases. With the wording “under an angle” it is understood that the light beam is not perpendicular and not parallel to the surface.
The tendency in the field of PLD is to coat increasingly larger surfaces of substrates. As the substrate must be positioned near the surface on which the light beam is projected, the space through which the light beam can be directed onto the surface decreases and the angle between the light beam and the surface decreases correspondingly, resulting in a more and more inhomogeneous energy distribution.